Winds of Chaos

When casting does a wizard need his hands free to gesture or is it purely a verbal action?

Partys elf mage has a broken arm and i agreed that that prob wouldn't impact on casting but when both hands full or arms tied up?

Also can a mage cast spells when "prone"?

Rules as written, no movent is required in any sense. Regardless of the requirements in lore, the game mechanics treat casting a spell as having the same requirements as blathering- you only need to be able to open your mouth and let nonsense flow out of it. The prone condition does nothing to restrict one's speech

Since my players often RP doing gestures whilst casting magic, I think I would house rule a -20 penalty, if their hands were tied, for the bigger spells. Petty spells would be exempt.